Improved propeller-screw



UNITED STATESN PATENT OEEICE.

WM. EDWARD DAvIS, oE JERSEY CITY, NEW JERSEY.

IMPROVED PRoPELLl-:R-SCREW.

Specification forming part of Letters Patent No. 56,907. dated August 7, 1866.

To all whom t may concern:

Beit known that I, WILLIAM E. DAvIs, of Jersey City, in the county of Hudson and State of N ew Jersey, have invented a new and Improved Propeller Screw, and I do hereby declare that the following is a full, clear, and exact description thereof, whichrwill enable others skilled in the art to make and use the same, reference being had to the accompanying drawings, forming part of this specification; in which- Figure l isa perspective end view of the screw-propeller. .Fig 2 is perspective side View of the same. Fig.3 isa plan of a single blade of circular form before being bent to shape. Fig. 4 is a longitudinal view, partially in section, of the screw-propeller. Fig. 5 is a plan of a single blade of rectangular form before being bent to shape. Fig. 6 is a view of single blade after being bent to shape.

Similar letters of reference indicate like parts.

My invention relates to screW-propellers for steainships; and it consists in constructing the screw .by the unison of separate blades fastened upon the shaft, the advantages of which are manifold. The screw is lighter,stronger, and cheaper than when cast solid. It is more effective as a propeller'on account of equality throughout in the thickness of the blades from` the center to the circumference--a form which places their sides at right angles to the line of motion of the shaft, and therefore enables them to exert greater impinging power upon the water in their revolutions than the old cast blades7 which are thick at the center an d taper off to a thin edge. rDhis improved form of the blades contributes a valuable element of power to a propeller, which will increase the speed of .vessels in any given number of revolutions of the screw.

Another very important acquisition secured.

by my mode of constructing a screw with separate blades is the facility it affordsof replacing a broken or injured blade, even at sea, at

trifling cost, which accident happening to a l solid east screw ruins it entirely, and during a voyage may endanger life and property. The blades of a screw are all alike and packed together closely, so that they are easily transstand my invention, I will proceed to describe its construction and operation.

Referring to Figs. 1 and 2, A A A A represent the blades in position when fastened together, B, the shaft on which they are hung; C, a hub or cylindrical block, hung loosely on the shaft `between the opposite sides of the blades at their point of fastening; D D, slipping collars, one on the extreme end of the shaft and the other on the shaft on the side of the screw which goes neXt the ship, and both of them on the opposite outer sides of the blades, supporting and bearing them up against the cylindrical block vC between them. Outside of the collarD,on the extreme end of the shaft, is a nut or screw-collar, E.

Fig. 4 is a section of the propeller, showing the mode of connecting the `blades with the shaft and fastening them.

Fig. 6 is a separate blade ready for forming a screw and attaching it to the shaft.

ber of blades forming the screw respectively. t

vWhen thus arranged with the cylindrical block C between them they are slipped on the shaft up against the inside collar D, which rests upon a shoulder on the shaft. The outside collar D is then crowded against the outer side of the screw-blades by the nut E, having been first moved to equidistant position on the shaft, as

represented by Fig. l. To hold them in this relation to each other and secure them in place rrnly, I put bolts t a. a a, Fig. l, through the `collars D D, passing through corresponding holes in the sides of the screw; or they may be fastened by feathering them onto the shaft.

Figs. 3 and 5 represent the blades dat, just as they are cut out of boiler-iron or other plate of suitable metal, No. 3 being a perfect circle and No. 5 rectangular on the exterior edge. The inner side of the blade in both isa true semicircle.

The holes b b are made for the shaft and l in the center of two smaller circles, forming the ends or sides ot' the blades, which are fastened together as above described, separated only by a slit in the metal plate of the ila-t blade. The curvilinear-sided triangular space c out out of the flat plate allows the ends of the blade to spread and form the opening between the screw and tbe shaft, as seen in Fig. 2.

For bending the flat blades to the desired eurvilineal shape for the screw, as represented by Fig. 6, they may be blocked up with the hammer when hot or formed With calenderrolls. 

